Watermarking is a process of embedding data into an image or an audio or video signal for preventing illegal copying as well as securing the copyright and ownership of data owner. The data that is embedded is called a watermark. Typically, the watermark corresponds to a code, a pattern, a logo, an image, or some form of identification information associated with the data owner. In general, the watermark is embedded into original data by adding a watermark signal to the original data. An algorithm accepts the original data and the watermark signal to be embedded and produces a watermarked data. Once embedded, the watermark remains within the original data when it is stored or transmitted. Subsequently, the watermark may be extracted at any later point in time to verify the owner of the original data.
However, due to changes or attacks to the original data, such as a host image, the watermark may suffer damages, thereby causing loss in information associated with the watermark. For example, the watermark embedded in the host image may be corrupted intentionally, to bypass or destroy the ownership information, or unintentionally through various transformations that occur while handling the host image. As a result, the watermark that gets extracted may not be completely identifiable or may not include all the necessary information required for tracing the host image and verifying the ownership information associated with the host image.
Therefore, there is a need for a method and apparatus for reliably embedding a watermark image in a host image that increases robustness of the watermark image against various kinds of attacks and damages.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention.